1. Field of the Invention
The present invention, generally, relates to tool drive devices known as ratchet type wrenches and, more particularly, to a new and improved structural arrangement for a reversible ratchet type wrench.
The industry has experienced many sincere efforts to develop ratchet type wrenches that are both reversible in the direction of the drive action and that will maintain a preset position once it is selected for such drive action. It was thought that the development of the frictional engagement roller as a replacement for the long used pawl and gear arrangement was the solution, finally, but several problems were revealed which prevented these promises from ever being realized.
2. Description of the Prior Art
U.S. Pat. No. 2,469,572 to Pratt that issued on May 10, 1949 describes an early arrangement of a reversible friction clutch wrench to eliminate lost motion in gripping and releasing a rotary shaft.
U.S. Pat. No. 3,621,739 to Seablom that issued on Nov. 23, 1971 describes a plurality of rollers that are wedged between a rotatable cylindrical member and cam surfaces located in radial recess openings.
U.S. Pat. No. 3,823,625 to Myers that was granted on July 16, 1974 describes a ball in each of a plurality of arcuate recesses with a separator between each ball and a biasing spring.
U.S. Pat. No. 4,669,339 to Cartwright, granted on June 2, 1987, describes rollers fitted in semi-cylindrical bores to be wedged with cam faces for providing a reversible, instantaneously gripping friction drive action for a wrench.
At first appearance, the structural arrangements of these prior wrenches have similarities in form with the present improved reversible wrench, but they differ in material aspects. These differences will become more readily apparent as the description proceeds and are essential to the effective operation of the invention, as well as to the realization of the advantages of a structure according to the present invention, which advantages are not available with the prior wrenches.